Boat superstructure



FIG. 1 is a side elevational view of a boat superstructure showing my new design, the left side elevational view being a mirror image of that shown;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof; and,

FIG. 4 is a rear elevational view thereof.

The broken lines shown in FIGS. 1, 3 and 4 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a boat superstructure, as shown and described. 